Inclined rotary gasifier waste to energy system

ABSTRACT

A gasifier system includes a reactor for receiving a wet feedstock which has a base and a container rotatably connected to the base such that a rotation of the container causes a mixing of the feedstock in an interior of the reactor. The interior is bounded by the base and the container. A space between the base and the container allows an entry of oxygen into the interior. The space has a dimension such that the feedstock is fully oxidized in a combustion area adjacent the base and such that the feedstock avoids combustion in a remainder of the interior. The reactor has a longitudinal axis inclined at an inclination angle relative to a horizontal line to promote the mixing of the feedstock in the interior.

RELATED APPLICATIONS

This application is a Divisional of U.S. national phase application Ser.No. 15/305,985 filed on Oct. 21, 2016, which is a 371 National Phase ofPCT/US2015/026854 filed on Apr. 21, 2015, which claims priority to U.S.Provisional Application No. 61/983,697, filed Apr. 24, 2014, entitledINCLINED ROTARY GASIFIER WASTE TO ENERGY SYSTEM, and U.S. ProvisionalApplication No. 62/118,458 filed on Feb. 19, 2015 entitled INCLINEDINDIRECT FLAMING PYROLYSIS ROTARY GASIFIER (IIFPRG) FOR WASTE TO ENERGYAPPLICATIONS, the entire disclosures of which are incorporated herein byreference.

GOVERNMENT RIGHTS STATEMENT

The invention disclosed herein was made at least in part with funding bythe U.S. Government, specifically the United States Department of theArmy under grant number W15QKN-08-1-0001. Therefore, the U.S. Governmenthas certain rights in this invention.

TECHNICAL FIELD

The present invention relates generally to waste to energy systems, andmore particularly to systems and methods for converting a wet feedstockinto a fuel.

BACKGROUND

Waste to energy systems may be utilized to generate electricity, reducea volume of waste or both. Such systems may rely on combustion to reducea volume of waste while creating heat which may be used to generatesteam and drive a turbine for generating electricity, for example.Gasification apparatus may also be used to generate synthetic gas fromsolid or liquid waste that may be used to fuel electrical generators,gas turbines, internal combustion engines, fuel cells, and combustionboilers, for example.

Waste to energy systems have been utilized for converting wet and drywastes to electricity. Such waste to energy systems have been found tobe particularly valuable in forward military applications where bothfacilities for waste disposal and fuel to drive electrical generatorsare in short supply. For example, waste to energy systems and methodsmay replace burn pits while reducing the use of liquid diesel fuel togenerate electricity for military applications.

One example of a waste to energy system is a gasifier or reactor whichinputs wet flammable waste and outputs synthetic gas among other things(e.g., oils, tar, ash and carbon black). Reactors may include rotatingportions which receive the wastes and may be oriented horizontally butmost often are configured as vertical columns and include various fixedbed or fluidized systems. Typical bed designs include fluidized bed,entrained bed, downdraft gasifier, and updraft gasifier. All of theseconfigurations require, to varying degrees, that feedstock material beof relatively small particle size, reasonably homogeneous, and have alow moisture content (e.g., less than 10%).

Usually, any energy associated with the removal of excess water prior toa feedstock being input to a reactor has to be supplied to the process.Drying and combustion processes generally utilize natural gas or someother auxiliary fuel.

Thus, a need exists for improved systems and methods for converting awet feedstock into a fuel.

SUMMARY OF THE INVENTION

The present invention provides, in a first aspect, a gasifier systemwhich includes a reactor for receiving a wet feedstock which has a baseand a container rotatably connected to the base such that a rotation ofthe container causes a mixing of the feedstock in an interior of thereactor. The interior is bounded by the base and the container. A spacebetween the base and the container allows an entry of oxygen into theinterior. The space has a dimension such that the feedstock is fullyoxidized in a combustion area adjacent the base and such that thefeedstock avoids combustion in a remainder of the interior. The reactorhas a longitudinal axis inclined at an inclination angle relative to ahorizontal line to promote the mixing of the feedstock in the interior.

The present invention provides, in a second aspect, a method for use inconverting a wet flammable feedstock into a gaseous and liquid fuelwhich includes providing a wet flammable feedstock into an interior of areactor having a base and a container connected to the base. Theinterior is bounded by the base and the container. Oxygen is allowed toenter a space between the base and the container to facilitatecombustion of the feedstock in a combustion zone adjacent the base suchthat the oxygen avoids passing through the combustion zone in thefeedstock to fully oxidize in the combustion zone. The container isrotated relative to the base to mix the contents of the interior of thecontainer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational view of a gasifier system of the presentinvention;

FIG. 2 is a side cross sectional view of a portion of the gasifiersystem of FIG. 1 loaded with feedstock;

FIG. 3 is another side cross sectional view of the gasifer system ofFIG. 1 empty of feedstock charge; and

FIG. 4 is a side elevational view of the gasifer system of FIG. 1 inconjunction with a schematic showing connections to other elements ofthe system.

FIG. 5 is a cross sectional view of a portion of the gasifier system ofFIG. 1 showing a bottom of reactor thereof;

FIG. 6 is a side cross sectional view of the nozzle assembly of thereactor of the gasifier system of FIG. 1;

FIG. 7 is a bottom view of the reactor showing the spring plate detailof the gasifier system of FIG. 1;

FIG. 8 is a side view of a portion of the gasifier system of FIG. 7;

FIG. 9 is a chart of an example feedstock mixture for use in thegasifier system of FIG. 1; and

FIG. 10 is a line chart depicting temperatures of an example of aprocess utilizing the gasifier system of FIG. 1;

FIG. 11 is a cross sectional view of an impingement scrubber andintegral oil separator for use with the gasifier system of FIG. 1 inaccordance with the present invention;

FIG. 12 is a block diagram view of a polisher for use in the gasifiersystem of FIG. 1 in accordance with the present invention;

FIG. 13 is a side cross sectional view of the polisher of FIG. 12;

FIG. 14 is a front cross sectional view of the polisher of FIG. 12; and

FIG. 15 is a bar chart depicting heating values for syngas producedusing the gasifier system of FIG. 1.

DETAILED DESCRIPTION

Each embodiment presented below facilitates the explanation of certainaspects of the disclosure, and should not be interpreted as limiting thescope of the disclosure. Moreover, approximating language, as usedherein throughout the specification and claims, may be applied to modifyany quantitative representation that could permissibly vary withoutresulting in a change in the basic function to which it is related.Accordingly, a value modified by a term or terms, such as “about,” isnot limited to the precise value specified. In some instances, theapproximating language may correspond to the precision of an instrumentfor measuring the value. When introducing elements of variousembodiments, the articles “a,” “an,” “the,” and “said” are intended tomean that there are one or more of the elements. The terms “comprising,”“including,” and “having” are intended to be inclusive and mean thatthere may be additional elements other than the listed elements. As usedherein, the terms “may” and “may be” indicate a possibility of anoccurrence within a set of circumstances; a possession of a specifiedproperty, characteristic or function; and/or qualify another verb byexpressing one or more of an ability, capability, or possibilityassociated with the qualified verb. Accordingly, usage of “may” and “maybe” indicates that a modified term is apparently appropriate, capable,or suitable for an indicated capacity, function, or usage, while takinginto account that in some circumstances, the modified term may sometimesnot be appropriate, capable, or suitable. Any examples of operatingparameters are not exclusive of other parameters of the disclosedembodiments. Components, aspects, features, configurations,arrangements, uses and the like described, illustrated or otherwisedisclosed herein with respect to any particular embodiment may similarlybe applied to any other embodiment disclosed herein.

In accordance with the principles of the present invention, systems andmethods for converting a wet feedstock into a fuel are provided.

In one example, a gasifier system 10 for converting a feedstock into asynthetic fuel gas (syngas 50) and liquid fuels is depicted in FIGS.1-4. Gasifier system 10 may be an Inclined Indirect Flaming PyrolysisRotary Gasifier (IIFPRG), which converts a flammable solid feedstockinto synthetic fuel gas (syngas) and oil.

Gasifier system 10 may include a reactor 15 having a rotating drum orcontainer 20 which is rotatable relative to a stationary base 30.Reactor 15 may be mounted on an incline 78 (e.g. greater than 22 degreesrelative to a horizontal line) which allows a feedstock 116 mixed withinert items to tumble downhill (i.e., toward a lower position) towardreaction boundary 118 within a reactor 15 as depicted in FIG. 2.Container 20 may be supported by rollers 22 and rotate axially driven bya motor 48, gearbox 46, and torque tube 44, for example relative toconstruction of reactor. An optimum rotational speed of the reactor isbetween 0.2 and 0.5 rotations per minute. Reactor 15 may be supported on4 radial support rollers 22 and at least one axial thrust roller 24 thatrides against axial thrust flange 26, for example. Additional rollerscould also be utilized depending on a size and shape of the container.

Base 30 may be rotatably connected to container 20 as indicated above.Container 20 may include a cylindrical wall 130 and a top 40, but couldbe formed of other shapes such that it is air-tight and rotatablerelative to base 30. Container 20 may be continuously welded along anaxial length thereof and all around top 40. Container 20 may be fullywelded airtight having no openings, except at a feed end (i.e., a bottomend 172).

An ideal inclination angle 78 of reactor 15 may be 40 degrees from thehorizontal, but angles greater or less than 40 degrees may be optimalbased on a size and an aspect ratio. The optimum aspect ratio of therotating cylindrical reactor vessel for an inclination of 40 degreesfrom the horizontal is 2.5 to provide sufficient volume to accommodatefeedstock while minimizing size to limit thermal energy losses. Aspectratios greater or less than this value are possible based on thediameter, inclination angle, and feedstock tumbling angle of repose.

Base 30 may include a feedstock input conduit 76 and an oil inputconduit 164. Feedstock 64 may be received in feed bin 66 and may bemunicipal solid waste, for example. Feed bin 66 empties into compressionchamber 68. Also the feedstock could be any flammable solid feedstockthat burns with an open flame including, but not limited to wood, energycrops, coal, construction and demolition wastes, agricultural wastes,sewage sludge, waste lubricants, and municipal solid wastes. A uniqueinclined rotational property of gasifier system 10 allows inertnon-flammable items to be mixed with the feedstock, avoiding the need toprepare and separate inerts items from feedstock prior to processing.Inert items such as metals, glass, stone products, and soils simply passthru the system and are discharged out of the gasifier through door 58as an ash, which results from the process. Ash door 58 opens and is abottom segment of swash plate 56. Ash door 58 is mounted on hinges 322and can swing open using handle 320.

As indicated, a feedstock 110 and an oil (e.g., a reflux oil) 54 are fedinto the reactor. Syngas 50 exits the reactor through a syngas exitconduit 134 located on a lower end of reactor 15 and which may bemounted above the axis of rotation of container 20. Stationary syngasexit pipe 134 extends a full axial length of the cylindrical rotatingreactor vessel, i.e., reactor 15. Syngas 132 enters the syngas exit pipe134 at a full uphill location 158, alleviating the possibility offeedstock entering the pipe and causing blockages. Wash oil 52 issupplied through a conduit 152 and exits through a notch 154. Syngas 156mixes with wash oil 52 at mixing point 160. Syngas 156 immediately coolsand a syngas oil mixture 162 flows downhill and exits the reactorthrough stationary base 60.

The gasifier may process solid feedstock without a need for pre-drying.Feedstock falls into a compression chamber 68. The feedstock handlingsystem uses a hydraulically powered piston 72 to drive ram 70 to bothcompact and push feedstock into reactor 15. Feedstock is exposed toexcessively high compaction forces, which mechanically removes excesswater by squeezing, which drains at point 74. The piston may cause thefeedstock 110 to be fed through feedstock input conduit 76 of base 60through an exit 112 into an interior 114 of container 20.

Feedstock processed may be dripping wet mixed wastes with moisturecontents exceeding 80% (i.e., wet basis, 80% water and 20% solids). Thefeedstock may be mechanically dewatered to a moisture content of lessthan 50% (wet basis) by squeezing feedstock to compressive stresses ofup to 2800 pounds per square inch using piston 70. Water may freelydrain by gravity from the feedstock during the compression stroke due towide clearances between piston 70 and compression chamber 68 and a steepinclination angle 78. Water may be collected in a holding tank (notshown). The feedstock may be compressed and densified during suchdewatering to remove air voids, preventing gases from flowing in conduit76 and also increasing a mass holding capacity of the reactor vessel 20.In an example, a geometry of compression chamber 68 may transition fromsquare (or rectangular) to round at the connection point with feedstockconduit 76, thereby providing a length of controlled frictional forcebetween the feedstock and the feed tube wall. This natural resistancemay provide sufficient force to allow the piston or ram to fullycompress the feedstock to the compressive forces necessary fordewatering and densification.

Reflux oil 54 may be pumped from a quencher 220 through oil inputconduit 164 and through oil exit 166 into interior 114. Oil 54 isthermochemically converted into syngas at reaction boundary 118. Thereactor 15 creates oil aerosols, which condense in quencher 200 as fluid224 (e.g., reflux oil). Additional oil may also be received intoquencher 220 from other sources and could, for example, be mineral oil,vegetable oil, animal fats and oils, used cooking oil, used crankcaseoil or other lubricants, or various mixtures of these components.

Base 30 may include a stationary nozzle 60 and a self-locating springloaded swash plate 56. The swash plate may contact or be engaged tobottom end ring 172 (FIG. 5) of container 20 such that a space 80 ispresent between plate 56 and bottom end 172.

As indicated, the feedstock may be partially densified when entering thereactor due to an activation of piston 70 or anthercompaction/dewatering mechanism. Such compressed feedstock may act as amaterial seal to prevent the entrance of air into the rotary gasifier atthe feed point 112. In particular, partially reacted feedstock, in theform of fixed carbon, may accumulate in the annulus 120 between thestationary nozzle 60 (i.e., base 30) and a rotating cylindrical reactorsleeve 174 (i.e., reactor 15). Combustion air, may enter through space80 described above may flow through the fixed carbon annulus 120,providing intense red hot burning coals within annulus 120. Oxygen isconsumed within annulus 120, providing intensely hot combustion gasesthat may consist primarily of carbon dioxide and nitrogen when reachinghot to cold interface boundary 118. The burning red hot layer of coalswithin annulus 120 acts as a rotary seal between the rotatingcylindrical reactor sleeve 174 and the stationary nozzle 60. Nomechanical seals between rotating and stationary elements are requiredor used.

Reactor 15 may be aspirated using enriched air or pure oxygen as a meansto enrich the energy content of the syngas by minimizing nitrogencontent. Enriched air or pure oxygen is fed into the cylindricalrotating reactor vessel using multiple gas injection tuyeres 324 thatare mounted directly to the stationary self-locating spring loaded swashplate 56 on the far downhill end of container 20, e.g., at space 80describe above. Oxygen is fed until the pressure at the swash plate isslightly positive (about +0.5 iwg positive pressure).

As depicted, swash plate 56 may be located on a lower end of container20 and may hold burning red hot fixed carbon within container 20 andevenly distribute a flow of aspiration (combustion) air from space 80into the lower or downhill end of the rotating cylindrical reactorvessel (i.e., reactor 15). As the fixed carbon burns to ash, the ash andclinkers may grind to fine powder between the stationary swash plate 56and rotating riding ring 172. Ash discharges to atmosphere through theair intake clearances (i.e., space 80) and falls into a centrallylocated collection pan located below (not shown). Further, swash plate56 may include an ash dump door 58 at the far downhill location tofacilitate the removal of large inert items such as stones, metals,glass, etc., that may accumulate within the reactor. The door may alsoserves as a means to fully dump remaining feedstock from the reactorinterior when desired.

The feedstock is thermo-chemically reacted at boundary 118 to fixedcarbon. This carbon burns, as red hot coals, to carbon dioxide, usingair, enriched air, or pure oxygen at the far downhill end or lower endof reactor 15. Combustion products consisting primarily of carbondioxide and nitrogen mix with and dilute the syngas 132, lowering theenergy content (heating value). The rotating action of the reactorvessel consistently tumbles a bed of the red hot coals within thegasifier vessel, allowing full and complete reactions, while alleviatingair gaps and blockages which could inhibit such reactions. The tumblingaction and inclination angle 78 allows the feedstock with excessive fineparticle size and plastic content to be processed without blockages.Fixed carbon is fully burned to ash and discharges with inert items(soil, stones, metals, glass, etc.) at the far downhill end of thegasifier through clearances (e.g., space 80) between swash plate 56 andriding ring 172, for example, or ash dump door 58.

The feedstock level within reactor 15 is monitored using internaltemperatures. Temperature sensors 168 and 170 measure the internaltemperature various axial distances that are mounted in thermo wells atthe end of the stationary concentric nozzle 60 (i.e., base 30). Thesetemperatures are used to monitor the level and temperature of thefeedstock charge within the reactor vessel and a cool temperature mayindicate the presence of raw wet feedstock at the measuring point. A hottemperature indicates the lack of feedstock at the measuring point.

Feedstock input conduit 76 may be stationary relative to container 20 asdescribed above, with nozzle 60 being concentric and extending intocontainer 20 to introduce wet feedstock (e.g., at about 50% moisturecontent or 50 lbs of water for every 100 lbs of wet feedstock) directlyinto the an Updraft Direct Flaming Line Flash Gasification (UDFLFG)reaction boundary 118. UDFLFG uses dramatic temperature gradients toflash dry and then flash devolatilize solid and liquid feedstock intosynthetic gas, oil aerosols, and fixed carbon. Air, enriched air, orpure oxygen is used to combust the remaining fixed carbon to create theheat required to sustain the process. Gasification occurs on a verynarrow boundary line 118 where the temperature differences can exceed2000 deg. F. over a very short distance, typically 1 to 6 inches inlength. Wet feedstock 110 that was fed through conduit 76 and entersreactor 20 at exit point 112, tumbles and forms a wet layer 114.Partially dried feedstock is pushed uphill and forms a dry layer 116.Feedstock in dry layer 116 continually mixes with fresh layer 114 asreactor shell 20 rotates. Feedstock is converted to gas and fixed carbonchar at the point of devolatilization at the UDFLFG boundary 118.Feedstock is continually consumed, diminishing layers 114 and 116,allowing temperature sensor 170 to be exposed, resulting in asignificant temperature increase. To sustain the process, additionalfresh feedstock 110 must be fed into wet layer 114 until sensor 170 isfully covered as indicated by a significant drop in temperature.

Feedstock input conduit 76 may be shaped (not shown) at exit 112 to opena bottom half of the feed pipe at a discharge point to force cold wetfeedstock directly into the UDFLFG reaction boundary 118. The ideal feedpoint aspect ratio is 0.5, but this value may vary based on the reactordiameter and inclination angle.

As described above, air or components thereof (e.g., Oxygen) enters thebottom of a hot burning char annulus 120 below UDFLFG reaction boundary118 via the space 80, causing fixed carbon to burn at temperaturesbetween 2000 and 2200 deg. F. within annulus 120.

The flow of oxygen into the reactor 15 may be self-regulating. Theaspiration of syngas flow 50 is kept constant, so if the temperaturedrops, a rate of feedstock gasification (gas production fromdevolatilizing the feedstock) drops, forcing more oxygen (air) to enterthe fixed carbon combustion zone annulus 120, quickly increasing thetemperature, which in turn increases the rate of gas production fromdevolatilizing the feedstock. Vice versa occurs when the temperaturebecomes too hot (more gas from feedstock and less oxygen enters thecombustion zone).

Condensate water 252 from gas drying may be thermchemically processedwithin reactor 15 in a controlled manner by chemically splitting waterinto flammable hydrogen and carbon monoxide gases using the water gasand water shift reactions. Condensate 252 enters superheater 254, whereliquid water 252 is converted into superheated steam 256 using hotexhaust gases 276. Condensate water vaporizes to superheated steam 256using excess exhaust heat. Superheated steam 256 is injected throughswash plate 56 directly into the burning red hot fixed carbon bedannulus 120 using multiple injection tuyeres 324. The degree of steamconversion to flammable gas is regulated based on the temperature withinthe burning fixed carbon bed. Additional amounts of waste water can beprocessed at times of excess thermal energy. Superheated steam 256 maybe mixed with air, enriched air, or oxygen to form mixture 330, which issupplied to distribution manifold 326. A supply conduit 328 suppliesmixture 330 to the injection tuyeres 324, which may have a distributionnotch 352, which is pointed in the direction of rotation of a bed flow354 to prevent the entrance of red hot coals and ash from annulus 120from entering and blocking the tuyeres.

Cold wet feedstock 110 and oil 54 (e.g., pyrolysis oil or reflux oil 224from quencher 220) are fed into reactor 15 separately as describedabove, but are fed directly into the UDFLFG boundary 118, pushing warmerand dryer feedstock uphill or further away from bottom end swash plate56. Intense heat and combustion gases directly contact the cold wetfeedstock and oil mixture, causing flash drying and flashde-volatilization into flammable syngas directly on boundary 118. Heattransfers over the boundary 118 by direct conduction, radiation, andforced convection. The thermochemical reactions may occur directly onthe boundary 118 between the intense heat from burning red hot coals inannulus 120 and cold wet feedstock 114. The temperature of the feedstockin layer 114 can increase from 150 to 2200 degree F. when passing overboundary 118 and entering into annulus 120. These temperature gradientsmay occur over one inch of linear distance at boundary 118 within thematerials in the container. The burning red hot coals within annulus 120may be maintained at a temperature of approximately 2200 degrees F. andmay be the sole combustion zone of the feedstock fed into container 20.Temperatures in the reactor reduce rapidly from the 2200 degrees F. inthe combustion annulus 120 to approximately 500 degrees F. when passingthrough wet feedstock layers 114 and 116 upon exit from the reactor atsyngas flow 158.

A layer of cold wet feedstock 114 starts to dry and mixes with a warmdry feedstock 116 above as a fresh flow of feedstock 110 into thegasifier stops. In this case, the wet feedstock dries and the two layers114 and 116 to merge into one, causing the overall temperature withinthe reactor to rise due to the drop in thermal load from drying. Thisexcess feedstock accumulates uphill of (i.e., above) the UDFLFG reactionboundary 118 when the gasifier is full of feedstock. The temperature ofthis unreacted or partially reacted feedstock gradually increases as itdries. The normal temperature of the feedstock within this zone isapproximately 250 to 400 deg. F., depending upon the operatingconditions within the reactor.

Tar aerosols may form during flash gasification at UDFLFG reactionboundary 118. Excess feedstock is desired uphill (i.e., above) theUDFLFG reaction boundary 118, to act as an internal filter to capturehigh molecular weight tars as the gas filtrates through the dryingtumbling bed. Syngas, tar aerosols, organic vapors, water vapor, andsteam form mixture 132 and pass through this layer of excess warm wetdrying feedstock 116 which is pushed uphill as excessive cold wetfeedstock 114 enters the reactor at 112. Heavy tar aerosols partiallycondense within both layers 114 and 116 of warm wet drying feedstock.These tars agglomerate onto the feedstock and are thermochemicallycracked into lighter molecular weight fractions when reaching the UDFLFGreaction boundary 118. These oils vaporize or form aerosols as thefeedstock enters the flash gasification boundary 118, thereby producinga pyrolysis oil (e.g., biocrude) that is condensed into a liquid inquencher 220. Oil production can be in excess of 30% of the grossfeedstock energy, depending on the plastics content of the feedstock.

Organic aerosols and vapors mixed with syngas and steam mix to form flow132, that exits reactor 15 using conduit 134 and condense to a liquid(i.e., oil) within quencher 220 by a sudden drop of temperature whenpassing through dispersion nozzle 222. Steam condenses to liquid water,which evaporates back into the gas in the form of vapor, absorbingthermal energy to cause quencher oil 224 to equalize between 165 and 175deg. F. Wet feedstock is required to produce sufficient moisture tosustain this evaporative cooling effect. Water must be added directly(not shown) into quencher vessel 220 when processing dry feedstock.Quencher oil 224, consisting of condensed oil from reactor 15 is used asthe primary liquid to clean the gas using impingement scrubber 234.Syngas exits quencher 220 through a conduit 226 and enters a gas mover230, which may be a positive displacement rotary lobe blower. A meteringpump 228 feeds quencher oil directly into conduit 226, flooding asuction side of gas mover 230 with oil mixed with syngas. Thepressurized mixture exits through conduit 232 and enters an impingementscrubber 234. A nozzle at the inlet of scrubber 234 accelerates themixture of gas and oil to excessively high velocities. This mixture ofhigh velocity fluids impinges directly on a static bed of oil at thenozzle exit. A high momentum exchange forces tars and particulates fromthe syngas into the oil. An oil separator 236 removes liquid oil fromthe syngas prior to entry into a syngas conduit 248. Liquid oil drainsthrough a conduit 238. This flow is split into a reflux metering pump242 and wash pump 240. Metering pump 242 feeds reflux oil back intoreactor 15 through a conduit 246 and oil input conduit 164. Wash oilpump 240 feeds wash oil 52 to reactor 15 through a conduit 244 andconduit 152. Reflux oil 54 continually circulates back into reactor 15through conduit 246 and oil input conduit 164, and is thermochemicallycracked into low molecular weight hydrocarbons that readily evaporateinto the syngas and exit the process as a vapor, greatly increasing theenergy value of the syngas. The particulates in the oil from impingementscrubber 234 eventually discharge from reactor 15 with the ash.

For example, hot syngas from reactor 15 drops in temperature whenentering the quencher 220. Oil aerosols, vapors, and steam mixed withthe synthetic gas immediately condense to a liquid when passing througha distribution nozzle 222. The moisture and organic vapors re-evaporateinto the syngas as a vapor when exiting the quencher. The amount ofenergy required to re-evaporate these liquids is higher than the thermalenergy entering the quencher, eliminating a need for cooling the oil(heat exchanger or cooler) present in other systems and processes. Thecondensed oil is continually thermochemically processed within thecombustion zone into higher vapor pressure lower molecular weightorganics as described above. These organics evaporate into the gas andleave the quencher in the form of vapor.

Excess oil is continually fed back into the reactor for reprocessing asreflux. For example, reflux oil 54 from quencher 220 is fed directlyinto the reactor at the point 166 (i.e., oil input conduit 164) whereraw feedstock is introduced 112, directly above the reaction boundary118. Heavy molecular weight organics are thermochemically cracked intolighter molecular weight organics by intense heat. Catalyst is notrequired. Thermal cracking of high molecular weight oils and tars intolow molecular weight organics naturally continues until the molecularweight and vapor pressure are within the range of less than C8 organicsto allow the liquid fuels to exit the process as a vapor that evaporatesdirectly into the syngas in the form of organic humidity. The flow ofreflux oil 54 adjusts to insure the oil creation rate matches thethermochemical conversion rate, insuring all created heavy organicsleave the process as organic humidity, which evaporates into exitingsyngas flow 50.

All feedstock moisture is flashed to steam, which exits the gasifier(i.e., reactor 15) in the superheated state mixed with syngas 132through syngas exit conduit 134. Steam condenses to a liquid and thenevaporates back into the gas as a vapor within quencher 220. Syngassaturated with moisture passes through a gas mover 230 and impingementscrubber 234. This moisture may be condensed back to liquid water in acondenser 250 portion of a gas cleaning system. The condensate waterreturns to reactor 15 to be thermochemically reacted into flammablehydrogen and carbon monoxide gases as described above.

The gas may be cleaned in multiple steps as shown by a gas polisher 262,then heated significantly above the pressure dew point using a reheater266, then delivered through a conduit 268 and mixed with combustion airfrom an intake filter 270, before being consumed as fuel within acombustion based device (e.g., a diesel engine 274 driving generator272). The gas may be used to substitute for up to 80% of the liquiddiesel fuel required in the configuration shown on FIG. 4, for example,in diesel combustion gensets or diesel-based electrical powergenerators. Syngas handles and burns similar to natural gas, which canbe used to fuel a variety of devices.

Reactor 15 may be surrounded by an insulated stationary shell 28. Acavity 34 forming an annulus for receiving heated gases may be boundedby an external surface 130 of reactor shell 20 and internal surface ofstationary shell 28. The gases may flow through an tangential input 32of shell 28.

Heat 126 may be indirectly transferred at surfaces 130 and 128 throughthe cylindrical rotating reactor shell 20 to provide additional thermalenergy to assist with feedstock drying and to increase the temperatureof the exiting syngas and superheated steam to about 450 to 700 deg. F.,depending on the level and moisture content feedstock layers 114 and 116within the gasifier.

Indirect thermal energy is provided from waste heat sources (e.g. tocavity 34 and reactor 15) such as diesel exhaust, which commonlydischarges to the atmosphere at 900 to 1200 deg. F. when a dieselgenerator is operating at load. Hot exhaust gases at 900 to 1200 deg. F.may thus blow against the gasifier shell and flow cyclonically 126within cavity 34 to provide optimum heat transfer. Alternatively, heatenergy may also be extracted from a radiator coupled to a combustiondevice with such energy being provided to cavity 34 via air heated bysuch a radiator.

Heat transfer pins and fins may be welded onto and thru the wall 20 atsurfaces 128 and 130 to increase the heat transfer area, to improveindirect transfer of thermal energy from the external heat source (e.g.,diesel exhaust) to interior feedstock flows 114 and 116, and syngas 132.Significant indirect heat transfer occurs through the wall of thereactor shell, heating feedstock and the mixture of syngas, superheatedsteam, organic vapors and aerosols. The mixture exits the reactor at theuphill end 158 at temperatures between 350 and 700 deg. F.

The heat provided to reactor 15 via cavity 34 and external surface 128and 130 of reactor 15 may maintain a temperature of interior 132 and maybring interior 132 to a desired temperature at a beginning of a processsuch that a start up time of the process may be minimized. The provisionof heat to cavity 34 as described may maintain, contribute to, augmentor otherwise control a temperature of interior 132.

Cool exhaust gases from cavity 34 exhaust to atmosphere through conduit36 as flow 138. The only emissions point to the atmosphere from theentire process is exhaust gas flow 38.

Stationary nozzle assembly 400 consists of all of the components shownon FIG. 6 as described above. Furthermore, a rotating cylindricalreactor sleeve 174 forms annulus 176, between outer shell 20 and sleeve174. Partially reacted cool feedstock 124 accumulates within annulus 176to shield the reactor shell 20 from excessive temperatures that couldmelt the shell. The accumulation of partially reacted feedstock 124 inannulus 176 prevents the need for refractory to protect the internalsurfaces of shell 20 and conducts heat away from sleeve 174.

An example of a process for gasifying waste is depicted in FIGS. 1-4.Raw feedstock 64 enters feed bin 66 and a compressor (e.g., a piston 70)compresses the feedstock at within compression chamber 68. Excessmoisture drains from the compressed feedstock at point 74. The moisturecontent of the feedstock at flow 110 is less than 50% (wet basis).

Wet feedstock thermo-chemically reacts within reactor 15. Oil (e.g.,excess reflux oil) may enter reactor 15 at boundary 118 though a conduitpipe 164 separate from feedstock conduit 76 as described above. Heavymolecular weight oil thermo-chemically cracks into lighter organicvapors when contacting the intensively hot burning char layer atboundary 118. Ash exits the process at swash plate 56 and ash dump door58. All feedstock moisture exits the gasifier in the form of superheatedsteam, mixed with syngas 132 and wash oil 52, exits the gasifier (i.e.,reactor 15) as mixture 136, and enters a quencher 220 to reduce thetemperature from more than 700 deg. F. down to about 175 deg. F., bybubbling the gas through a liquid filled column 224 at dispersion nozzle222. Quencher liquid 224 in quencher 220 is primarily pyrolysis oilcreated by the process described herein, but may contain condensatewater, mineral oil, vegetable oil, animal fats and oils, used cookingoil, used crankcase oil or other lubricants, or various mixtures ofthese components that may be intentionally added directly to thequencher for disposal in the process. Another purpose of the quencher isto prevent explosions in downstream equipment by using liquid 224 toextinguish any flaming embers that may exit the gasifier with thesyngas. Superheated steam flash condenses to water and thenre-evaporates in the form of humidity, which saturates the syngas withinexit conduit 226. Evaporation causes a significant refrigeration effectthat provides sufficient thermal energy to cool the syngas and condensethe superheated steam within quencher 220. Recovered condensate waterfrom condenser 250 may be added directly to the quencher vessel if thefeedstock is dry (less than 20% moisture on a wet basis), providingsufficient moisture to sustain evaporative cooling.

Saturated syngas exits the quencher through conduit 226 at slightlynegative pressure and mixes with oil 224 from quencher 220 usingmetering pump 228 prior to entering positive displacement blower 230.The blower serves as the primary means to aspirate the system. A slightamount of quencher liquid may be injected using metering pump 228 tolubricate the blower and provide fresh scrubbing liquid to impingementscrubber 234. Slightly pressurized syngas exits the blower throughconduit 232.

Syngas is first cleaned in impingement scrubber 234, where high momentumexchange between the gas and liquid removes the high temperature dewpoint tars and particulates. The impingement scrubber internallyrecirculates the oil multiple times prior to draining. The top portionof the scrubber contains a liquid separator 236. Hot liquids drain fromthe scrubber through conduit 238 and are returned to reactor 15 usingpumps 242 and 240. Reflux meeting pump 242 regulates the flow of refluxoil through conduit 246 and varies the flow to insure the oil level 224in quencher 220 remains constant during operation. Wash oil pump 240delivers the remaining oil as wash oil 52 through conduit 244 andconduit 152.

Impingement scrubber 234 and integral oil separator 236 are shown inFIG. 11 as a cross sectional view 500. Impingement scrubber 234 works ona principal of high momentum exchange between fluids to remove high dewpoint tar aerosols (e.g., over 155 deg. F.) and particulate matter fromthe syngas stream. A mixture 501 of syngas and oil from conduit 232 in aratio of 30:1 by volume is supplied to a nozzle 502. Mixture 501accelerates to a velocity at point 504 approaching half the speed ofsound (30,000 ft/min), although velocities up to the speed of sound arepossible at the cost of additional pressure drop. A nozzle 50 extendsinto a lift pipe 510, creating a relative suction at a point 522. An oil514 flows downward in annulus 526 by gravity and by suction at point522. Oil at static velocity enters lift pipe 510 at point 522, where ahigh velocity mixture 504 of syngas and oil impinges at high momentumexchange at a point 506 to form a mixture 508, which travels up the liftpipe and hits an impingement plate 512. A primary baffle 516 directs amajority of oil from mixture 508 to flow down an annulus 526. Syngas andexcess oil from mixture 501 exits thru ports 524. Oil from mixture 501is directed downward by a secondary baffle 518, allowing oil aerosolsand droplets to disengage from the exiting scrubbed syngas 528. Anexiting syngas 528 flows into greater flow area 535, resulting in afurther drop of an exiting syngas flow velocity 534, allowing theremaining oil droplets to disengage and fall into oil pool 532. Oildischarge conduit 238 extends into the separator vessel at a point 530to regulate a level of an oil reservoir 532. An excess oil 520 drainsfrom oil separator 236 through conduit 238. Syngas with oil droplets 538enter a low velocity area 535, where additional oil droplets disengageand flow into reservoir 532. An oil free syngas 536 exits throughconduit 248.

Saturated syngas exits oil separator 236 and enters condenser 250 usingconduit 248, where the gas is cooled to within 20 degrees of ambienttemperature. Liquid condensate and syngas exit the cooler and enters acondensate separator (not shown). Liquids drain from the separator andenter conduit 252, which delivers the liquid water to superheater 254.Thermal energy from exhaust 276 converts the condensate from liquid tosuperheated steam that enters conduit 256 and enters into reactor 15using injection tuyeres 324 (mounted in swash plate 56). Steam isthermochemically converted to flammable hydrogen and carbon monoxidegases using the water gas reaction. Liquid condensate is cracked intoadditional syngas (i.e., syngas 50) within reactor 15. A flow ofcondensate from the condenser 250 to reactor 15 is regulated by a valvebased on the temperature of the burning fixed carbon bed in annulus 120in the reactor.

Syngas with moisture content of less than 3.5% exits the condenser 250and enters gas polisher 262 using conduit 260. The polisher mechanicallyslings a glycol based polishing liquid into the syngas stream using ahigh momentum exchange to remove any remaining particulates and low dewpoint tars. The mixture enters a glycol separator (not shown) where theliquids are captured and recirculated back to the polisher.

FIG. 12 depicts polisher 262 shown as system 600, which removes low dewpoint organic tar aerosols and remaining particulates. A polishingliquid 612 may be ethylene glycol, propylene glycol, or any low vaporpressure solvent, for example. Polishing liquid 612 discharges from acyclonic separator 610 and passes through a strainer 614 to remove largeparticulates. A cool polisher liquid 616 enters a booster pump 618 toinsure a constant flow of liquid. A heat exchanger 624 warms polishingliquid 616 to maintain an identical temperature to the exiting syngasfrom condenser 250. Thermal energy is provided to heat exchanger 624using a hot heat transfer fluid 620 and a returning cool heat transferfluid 622. A warm polishing liquid 602 mixes with a dry syngas 601 fromconduit 260 prior to entering a rotary polisher 604.

Liquid and gas (i.e., warm polishing liquid 602 and dry syngas 601 enterrotary polisher 604, where the liquid is mechanically accelerated tohigh velocity. High velocity liquid impinges on the relatively staticgas, resulting in a significant momentum exchange that drives tar lowdew point tar aerosols and particulates out of the gas and into thepolishing liquid. The mixture of syngas and polisher liquid exit therotary polisher in conduit 606 and enter cyclonic separator 610, wherethe polishing liquid 612 is cyclonically separated from the syngas. Asyngas 626, free of tars and particulates, exits cyclonic separator 610through conduit 264. Tars and particulates agglomerate in the bottom ofcyclonic separator 610 and are eventually captured in strainer 614.

FIGS. 13 and 14 depict internal components of rotary polisher 604. FIG.13 is a side cross sectional view 704 of polisher 604 of FIG. 12 whileFIG. 14 is a front cross sectional view 702 of polisher 604. Syngas anda polishing liquid (i.e., warm polishing liquid 602 and dry syngas enterpolisher 604 as a mixture 722 and directly hit a face of a rotatingimpellor 710. A shaft 708 is driven by a rotary motor (not shown) and issupported and sealed by bearing housing 706. Polishing liquid ismechanically slung into the relatively static syngas stream at highmomentum exchange within flute housing 712 by impeller 710. A syngas 601and a polishing liquid 602 exit flute housing 712 by two or moretangential outlets 714 and 716. A mixture of syngas 601 and polishingliquid 602 cyclonically rotates (718, 720, & 721) within the polisherhousing to provide additional washing of syngas by momentum exchangeprior to exiting through a tangential outlet 724 and conduit 606.

Clean polished syngas exits the glycol separator saturated and entersthe gas reheater 266 using conduit 264. Reheater 266 is heats the syngasto at least 30 degrees F. above the dew point to avoid liquid watercondensing within exit conduit 268. Gas exits reheater 266 atapproximately 50% relative humidity.

As described above, the feedstock or waste received in reactor 15 may beformed of waste with a mix similar to that of municipal solid waste orcould have another mix. An example of the components of a typicalwastestream that could be utilized as a feedstock is provided in FIG. 9.The mix typical for municipal solid waste used in the described processprovides oil (e.g., biocrude) from quencher 220 which may be input intoreactor 15 which is more advantageous relative to an amount of syngasproduced relative to a waste having less petroleum product (e.g.,plastics) content. Alternatively, any other material possessing anenergy value and capable of being gasified to a flammable gas may beused as the feedstock.

Further, control and monitoring of the gasification system describedabove could be performed using a Programmable Logic Controller (PLC).Continuous temperature and pressure data could be monitored at variouslocations in the system (e.g., within reactor 15 such as in container20) and transmitted wirelessly to a standalone Personal Computer. In oneexample, as depicted in FIG. 10, temperature data was measured bythermocouples at 4″ and 20″ from a feed point and within gasifier exitconduit 134. Temperatures within the reactor may vary throughout aparticular time period run and such temperatures may be used as anindicator to adjust a feed rate of a reactor (e.g., reactor 15). Whenusing a PLC as described above, at points in time when a temperaturewithin a reactor dips, a reactor may signal that additional feed (i.e.,feedstock or waste) should be supplied. In the example using the wasteof FIG. 9 and temperatures of FIG. 10., temperatures in a combustion bed(e.g., annulus 120) were measured using a probe to be as much as 2200deg. F. Thermocouples placed along the longitudinal centerline of thereactor indicated that the temperatures drop at the reactor exit pointto between 400 and 500 deg. F. as indicated in FIG. 10.

As described above, syngas produced by the systems and methods describedherein may be mixed with diesel fuel at a ratio of up to 80% syngas and20% diesel fuel to power a diesel engine to produce electricity inremote locations, for example. A spark ignition internal combustionengine (Otto cycle) can operate on 100% syngas, depending on the type offeedstock processed. The syngas produced is similar to natural gas andcan be used to fuel a variety of devices (boilers, heaters, etc.) thatcurrently operate on gaseous fuels. The syngas produced has a highheating value with a flammability limit that sustains combustion withminimal flame separation, i.e., a high heating value (HHV) of about 100to 110 BTU/scf. Anything higher than this will sustain combustionreliably. Flame temperatures similar to natural gas (>1700 deg. F.) wereobserved when combusting syngas with a HHV of 145 BTU/scf. Examples ofsuch heating values for syngas produced using the systems and methodsdescribed above using different wastes are depicted in FIG.15.

Further, the waste reduction systems and methods described herein may beutilized to generate electricity and reduce a volume of waste, forexample, from a wet feedstock such as a waste stream at a forwardmilitary installation. Also, possible uses within the private sectorcould be handling waste relative disaster relief efforts, distributedpower generation, municipal solid waste reduction, biomass energyprojects, agricultural waste conversion, and large scale powergeneration using integrated gasification combined cycle.

Also, although the above described process includes a step of densifyinga feedstock prior to it entering interior 114, the feedstock may have amoisture content of up to 50 percent prior the feedstock enteringinterior 114. Such waste could start out at such a moisture percentageor it could have its moisture reduced (e.g., from up to 75 percentmoisture on a wet basis) using a compressor (e.g., piston 70 or ram) orother mechanism.

While several aspects of the present invention have been described anddepicted herein, alternative aspects may be effected by those skilled inthe art to accomplish the same objectives.

1. A method for use in converting a wet flammable feedstock into a gaseous and liquid fuel, the method comprising: providing a wet flammable feedstock into an interior of a reactor having a base and a container connected to the base, the interior bounded by the base and the container; allowing oxygen to enter a space between the base and the container to facilitate a combustion of the feedstock in a combustion zone adjacent the base such that the oxygen avoids passing through the combustion zone and the feedstock is fully oxidized in the combustion zone; and rotating the container relative to the base to mix contents of the interior of the reactor.
 2. The method of claim 1, wherein the providing the wet flammable feedstock comprises the feedstock entering the interior above the combustion zone.
 3. The method of claim 1, wherein the reactor has a longitudinal axis inclined at an inclination angle relative to a horizontal line to promote the mixing of the feedstock in the interior.
 4. The method of claim 3, wherein the inclination angle comprises an angle of greater than 22 degrees relative to the horizontal line.
 5. The method of claim 1, wherein the providing feedstock comprises providing the feedstock through a feedstock input in the base.
 6. The method of claim 1, further comprising providing an oil into the interior above the combustion zone.
 7. The method of claim 6, wherein the providing the oil comprises providing the oil through an oil input conduit that extends a length of a syngas outlet conduit, the oil input conduit providing a continual flushing and cooling of the syngas outlet conduit.
 8. The method of claim 1, further comprising an output syngas flowing through a syngas output conduit in the base, the output extending into the rotatable container substantially above a mixing layer of the feedstock.
 9. The method of claim 1, further comprising an output syngas flowing from the interior to a quencher and providing a condensate oil from the quencher into the interior above the combustion zone.
 10. The method of claim 1, further comprising coupling an outer surface of the container to a source of heated gas and controlling a temperature of said container using the heated gas.
 11. The method of claim 10, wherein the coupling comprising providing the heated gas to a temperature control cavity bounded by an inner surface of an outer casing and an outer surface of the container such that the gas provided to the cavity controls a temperature of said container.
 12. The method of claim 10, wherein the heated gas comprises diesel exhaust from a diesel engine.
 13. The method of claim 1, further comprising temporarily opening a portion of the self-locating floating plate relative to the reactor to allow a withdrawal of an excessive amount of fully combusted feedstock and non-combustible items mixed with the feedstock.
 14. The method of claim 1, further comprising supplying water through the space to the water into a flammable gas.
 15. The method of claim 1, wherein the providing the feedstock and the rotating cause the feedstock to form a continuous ring within the combustion zone on the base in the reactor. 